Approximately 100 subjects will be selected for study of possible neurologic damage as a result of asymptomatic increased lead burden. Fifty individuals, designated as the study group, will be those persons working at a secondary lead smelter and with blood lead levels in the range of 60-80 mcg%. The control group of equal size and drawn from a lead-free plant will be matched to the study group by the indices of race, sex, age, and length of work experience on the job. Neurological measurements obtained will be correlated with various indices of body lead burden. Also, plasma lead will be correlated with neurological findings to determine if it is a better indication of lead absorption than the commonly used whole blood lead value.